How effectively amylase digests starch.

Method

* Measure 10cm of starch and 2cm of amylase and put in 2 different test tubes.

* Measure the temperature of the liquids.

* Once it has reached the temperature you want mix the liquids together and start timing.

* Every 10 seconds take a drop of the reactants out and add to the iodine.

* If the iodine turns blue or black carry on with the experiment. If the iodine stays red or brown stop the experiment and record the time taken.

* Do each temperature three times and then find the average. To find the average I will add together the 3 times and divide it by 3.

* Repeat this experiment with nine different temperatures.

Diagram

Prediction

I predict that when the temperature gets above 40?C the collision of the enzymes will get to high that starch and amylase will not react with each other as well. I predict that it will take quite a long time for the starch and amylase not to react anymore for the first temperature. For the following temperatures I think that the time will go down. I think that when it gets to about 40°C the time will start increasing again.

I think that when I plot a graph it will look something like this.

Explanation

Collision theory

The chemicals need to collide for a reaction to take place. If the temperature is increased then the particles will move around faster therefore a collision is more likely to take place, so the rate increases. This is for temperatures below 40?C.

Enzymes denature when temperature is above 40?C.

Amylase and starch are like lock and key.

If it does not fit anymore as there is a change in PH or temperature. The site would be damaged and the enzyme does not work.

Results Table

Temp °C

2

3

Average

Rate

26

340

370

370

360

0.00278

28

370

380

360

370

0.00270

30

270

280

280

277

0.00361

32

240

260

260

253

0.00395

34

240

250

240

243

0.00412

36

250

240

230

243

0.00412

38

210

230

220

220

0.00455

40

50

30

20

35

0.00741

44

250

230

260

253

0.00395

48

350

340

330

340

0.00294

Conclusion

Results from graphs

On the time and temperature graph the line of best fit was in a U shape. A few of the results did not fit in properly, only one did not fit in with the results at all.

I got these results because when the temperature got above 38°C the starch and amylase did not react as well anymore because the amylase denatured.

On the temperature and rate graph the results was like an upside down U. The graph is just the same as the other one except it is upside down and back to front. To work out the rate divided the time by 1.

I predicted that when the temperature gets above 40?C it would not work as well because the collision will get too high. It is shown in my graph and results table that my prediction is correct.

Evaluation

I have three anomalous results that did not fit the trend. 40°C was quite a lot out of it. 26°C and 36°C fitted the trend but were quite far off the line of best fit. 40°C was a third of the time less. The first experiment that I did which was 26°C did not fit the trend at all. I think this is because it was the first experiment I did and I was not used to doing the experiment. Next time I do an experiment I will do the first one more times than the rest so I can get used to the experiment and get more accurate results.

I think that my experiment got quite accurate results I because I came up with the same trend as I predicted. I only got 3 out of place results. To improve my results I could repeat each experiment 5 times instead of three, as this would be more accurate. I could also experiment with temperatures at a greater range. I could use micro pipettes to make the experiment more accurate.

A Further experiment that I could do to extend the investigation is that I could use human amylase instead of bacterial amylase.

Here is the method of this experiment

* Wash mouth out with water

* Chew paper for a little while as this produces more saliva

* Spit into a beaker

* Measure 10cm of starch and 2cm of amylase and put in 2 different test tubes.

* Measure the temperature of the liquids.

* Once it has reached the temperature you want mix the liquids together and start timing.

* Every 10 seconds take a drop of the reactants out and add to the iodine.

* If the iodine turns blue or black carry on with the experiment. If the iodine stays red or brown stop the experiment and record the time taken.

* Do each temperature three times and then find the average. To find the average I will add together the 3 times and divide it by 3

* Repeat this experiment with nine different temperatures

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Harpreet Sekhon